Two research groups investigate technical coatings for additive manufacturing

Researchers from Sirris and the Fraunhofer Institute for Applied Polymer Research IAP have investigated technical coatings for additive manufacturing (TCAM) in a joint project, with results described as ‘promising’.

The two partners have concluded that additive manufacturing (AM) in combination with established technologies provides better capabilities and more possible applications than AM alone.

Additive manufacturing has many advantages such as custom manufacturing, flexible production and easy customisation. Yet many products have a high surface roughness and porosity. The post processing of the thus fabricated parts is time consuming and often a significant cost factor for manufacturers. Technical coatings could open up possibilities for the market, especially in industrial production.

AM describes the construction of an object layer by layer using a 3D-model. The technologies vary but 3D printing is probably the best known. However, selective laser sintering (SLS), stereolithography (SLA) or material jetting (MJ) play important roles in the AM market.

While the first AM technologies were developed for rapid prototyping, today, AM is taking the leap into industrial production. It is one of the important future technologies that will influence the manufacturing market and beyond. The industry can profit from AM with its production of on-demand capabilities, flexible adaptability and the possibility to produce small quantities. However, the surface of the fabricated components is usually very rough and porous.

Patrick Cosemans from Sirris Flanders said: "If we only polish our finished components, it takes a long time, and especially with fine, detailed features, we change their shape. It comes to abrasion, which we want to avoid. With the Fraunhofer IAP we have developed possibilities to overcome the current problems, especially the porous and rough surface, in additive manufacturing."

With technical coatings, the Sirris and Fraunhofer researchers were able to improve AM-produced parts regarding surface roughness and porosity. It turned out that the combination of lacquering and polishing is the most efficient technique for surface optimisation in AM. In addition, components can be functionalised further by using lacquers or surface treatments. In the current project, the scientists metallised the smoothed components.

Dr. Andreas Holländer, expert in surface technology and leads the research group at Fraunhofer IAP: “Today, with the transition from rapid prototyping to industrial production, the demands on AM-manufactured components are growing. Being able to warrant consistent material quality is essential for industry producers. In addition, demands on the surface quality are growing.

"With years of expertise in surface treatment, we are able to meet a wide range of requirements. We analysed each part in the first step to determine the specific properties. Afterwards we were able to activate, paint, and polish and, in this case, metallize the respective surface with the appropriate method."

Conventional production methods often reach their limits with complex components. The more complex a component, the more difficult and expensive it becomes in conventional production. AM opens up possibilities to produce complex components faster and more cost-efficiently. With AM, a component that would conventionally consist of many individual parts and would have to be assembled can be created in one step.

Dr. Holländer said: "It is important that every part of the component’s surface has the required quality. In complicated parts, some surfaces are difficult to reach. With the appropriate surface treatment technology, which in future will even be integrated into the AM machines, we are able to functionalize even complex components completely."